Chemically Degradable Carbon Dioxide‐Incorporated Polyurethane From Biomass‐Derived Polyester Polyols as Sustainable Adhesives

Polyurethane (PU) adhesives are extensively employed in flexible packaging owing to their strong adhesion and excellent wettability. However, most conventional PU adhesives are petroleum-based, which has driven growing interest in biobased alternatives. In this article, we synthesized biobased PU adhesives for flexible packaging applications using 2,5-furandicarboxylic acid (FDCA) and carbon dioxide (CO₂). FDCA-based polyols (FPs) (2500-3500 g mol^-1) with processable viscosities were prepared from FDCA, succinic acid, and 1,3-propanediol. To further enhance adhesion by increasing hydrogen-bond density, the diol and triol containing urethane moieties were synthesized via CO₂-utilization technology. In T-peel tests, the adhesives crosslinked with CO₂-based triols exhibited the highest adhesion strength (986 gf/25 mm) and were compared with those crosslinked using petroleum-derived trimethylolpropane (TMP). The prepared adhesives exhibited low glass transition temperature (from -28 to -18°C), ensuring flexibility at room temperature. In addition, the synthesized adhesives could be degraded through base-catalyzed transesterification in ethanol/ethyl acetate, enabling clean substrate recovery. These sustainable FDCA/CO₂-based PU adhesives demonstrate strong potential as alternatives to petroleum-derived adhesives for flexible packaging.